<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>css样式演示</title>
    <style>
        #two{
            font-weight: lighter;
        }
        #one{
            font-weight: bold;
            background-color: bisque;
            width: 100px;
            height: 100px;
            border: 1px #1b6d85 solid;
        }
    </style>
</head>
<body>
    <div id="one">我是一个div</div>
    <div id="two">我也是一个div</div>
    <div id="three">我还是一个div</div>
</body>
</html>